Method for locating a radio tag

Abstract

The invention further relates to a radio tag with a communication stage and a logic stage that interacts therewith The invention relates to a method for locating a radio tag whose position is unknown, wherein in a group of radio tags, in particular designed as electronic price-indicating devices, a locating signal is either a) emitted by one or more radio tags whose position is known and received by the radio tag whose position is unknown or b) emitted by the radio tag whose position is unknown and received by one or more radio tags whose position is known, and, in both cases a) and b), the reception quality for the locating signal is determined and provided, for the radio tag receiving the locating signal, as a basis for narrowing down the position of the radio tag whose position is unknown.

The invention claimed is: 
     
       1. A method for locating a radio tag (T 17 ) whose position is unknown, wherein, in a group of radio tags (T 1 -T 18 ) that are allocated by radio to only a single access point, the radio tags (T 1 -T 18 ) communicate with the access point in a normal mode using a time slot communication method, wherein, according to this time slot communication method, a defined number of time slots is available in a defined time unit, and one or more radio tags (T 1 -T 18 ) are allocated to one of the time slots, and each radio tag (T 1 -T 18 ) can be individually addressed in its time slot, so as to receive data or commands from the access point and/or transmit data to the access point,
 a locating signal (On): 
 a) is either transmitted by one or more radio tags (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known and received by the radio tag (T 17 ) whose position is unknown, 
 b) or transmitted by the radio tag whose position is unknown (T 17 ) and received by one or more radio tags (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known, 
 
       and, in both cases a) and b), the reception quality (Qn) of the locating signal (On) is determined and provided at the radio tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ; T 17 ) receiving the locating signal (On) in order to narrow down the position of the radio tag (T 17 ) whose position is unknown 
       wherein the radio tag (T 17 ) whose position is unknown and/or at least one radio tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known exit(s) the time slot communication method so as to transmit or receive the locating signal (On), and 
       wherein, after the locating signal (On) has been transmitted or received, the affected radio tags (Tn) again join the time slot communication method, and return to the normal mode, 
       wherein the affected radio tags (Tn) independently calculate the earliest possible time for joining. 
     
     
       2. The method according to  claim 1 , wherein
 the radio tag (Tn) whose position is known and that receives the locating signal (On) transmits the evaluated reception quality (Qn) to a data processing device ( 5 ), and the data processing device ( 5 ) narrows down the position of the radio tag (T 17 ) whose position is unknown, knowing the position of the radio tag(s) (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known and taking into account the reception quality (Qn) received by the respective radio tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known. 
 
     
     
       3. The method according to  claim 1 , wherein
 the radio tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known that transmits the locating signal (On) transmits the locating signal (On) along with its identifier (Kn), and wherein 
 the radio tag (T 17 ) whose position is unknown that receives the locating signal (On) reevaluates the locating signal (On) with respect to the identifier (Kn) transmitted along with the locating signal (On), and provides a data pair (Dn) comprised of the identifier (Kn) and accompanying reception quality (Qn). 
 
     
     
       4. The method according to  claim 3 , wherein the radio tag (T 17 ) whose position is known and that receives the locating signal (On) transmits the data pair (Dn) to a data processing device ( 5 ), and the data processing device ( 5 ) narrows down the position of the radio tag (T 17 ) whose position is unknown, knowing the position of the radio tag(s) (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known and taking into account the data pair (Dn) received by the respective radio tag (T 17 ) whose position is unknown. 
     
     
       5. The method according to  claim 1 , wherein the tag (Tn) intended for transmitting the locating signal (On), in particular the tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known, is switched from its normal mode into a search mode by a received search command, wherein the locating signal (On) and/or the time for transmitting the locating signal (On) and/or the frequency of transmitting the locating signal (On) is determined in the search mode. 
     
     
       6. The method according to  claim 1 , wherein the tag (Tn) intended for receiving the locating signal (On), in particular the tag (T 17 ) whose position is unknown, is switched by a received locating command from its normal mode into a locating mode, wherein a reception readiness for receiving locating signals (On) exists in the locating mode for a locating signal reception duration (OED). 
     
     
       7. The method according to  claim 6 , wherein
 the locating signal reception duration (OED) is designed so that all radio tags (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known and that are involved in the search for the radio tag (T 17 ) whose position is unknown can transmit their locating signal (On) at least one time within the locating signal reception duration (OED), but preferably several times. 
 
     
     
       8. The method according to  claim 6 , wherein
 the radio tag (Tn) intended for receiving the locating signal (On), in particular the radio tag (T 17 ) whose position is unknown, stores a data pair (Dn), comprised of the identifier (Kn) and accompanying reception quality (Qn), for each locating signal (On) received during the locating signal reception duration (OED) for later use. 
 
     
     
       9. The method according to  claim 8 , wherein
 the radio tag (Tn) intended for receiving the locating signal, in particular the radio tag (T 17 ) whose position is unknown, only transmits one or more stored data pairs (Dn) after the locating signal reception duration (OED) has expired. 
 
     
     
       10. The method according to  claim 1 , wherein the radio tag (T 17 ) whose position is unknown exhibits an indicating device, wherein the latter is used to visualize status information, which represents its internal or system-wide status as a radio tag whose position is unknown that is to be located. 
     
     
       11. The method according to  claim 1 , wherein a calibration communication with an access point (X 1 , X 2 ) whose position is known is performed with the radio tags (Tn), wherein the reception quality (Qn) is determined for each involved radio tag (Tn), and a relation is defined between the determined reception quality (Qn) and the position for the respective radio tag (Tn) whose position is known. 
     
     
       12. The method according to  claim 1 , wherein a data processing device is used to select aforesaid group of radio tags (T 1 -T 18 ) from the totality of tags (Tn) in a system, in particular from the totality of radio tags allocated to a radio communication device, in particular the access point. 
     
     
       13. A system ( 4 ) for locating a radio tag (T 17 ) whose position is unknown, comprising a group of radio tags (Tn) that are allocated by radio to only a single access point, wherein
 the radio tags (T 1 -T 18 ) communicate with the access point in a normal mode using a time slot communication method, wherein, according to this time slot communication method, a defined number of time slots is available in a defined time unit, and one or more radio tags (T 1 -T 18 ) are allocated to one of the time slots, and each radio tag (T 1 -T 18 ) can be individually addressed in its time slot, so as to receive data or commands from the access point and/or transmit data to the access point, wherein
 a) either one or more radio tag(s) (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known is/are designed to transmit a locating signal (On) and the radio tag (T 17 ) whose position is unknown is designed so that the locating signal (On) can be received as soon as the radio tag(s) (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known have transmitted it, 
 b) or the radio tag (T 17 ) whose position is unknown is designed to transmit a locating signal (On), and one or more radio tag(s) (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known are designed so that the locating signal (On) can be received as soon as the radio tag (T 17 ) whose position is unknown has transmitted it, 
 
 and in both cases a) and b), the radio tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ; T 17 ) that receives the locating signal (On) is designed to evaluate the locating signal (On) with respect to the reception quality (Qn) and to provide the determined reception quality (Qn) as the basis for narrowing down the position of the radio tag (T 17 ) whose position is unknown, 
 wherein the radio tag (T 17 ) whose position is unknown and/or at least one radio tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) whose position is known is/are designed to exit the time slot communication method so as to transmit or receive the locating signal (On), and 
 wherein the radio tags (T 1 -T 18 ) are designed to again join the time slot communication method and return to the normal mode after the locating signal (On) has been transmitted or received, and 
 wherein the radio tags (T 1 -T 18 ) are designed to independently calculate the earliest possible time for joining. 
 
     
     
       14. The system according to  claim 13 , wherein
 each radio tag (Tn) transmitting the locating signal (On) is designed to generate and transmit a locating signal (On) that exhibits the identifier (Kn) of the radio tag (Tn), and wherein 
 each radio tag (Tn) receiving the locating signal (On) is designed to evaluate the received locating signal (On) with respect to the identifier (Kn) transmitted with the locating signal (On) and generate a data pair from the identifier and accompanying reception quality (Qn). 
 
     
     
       15. The system ( 4 ) according to one of  claim 13 , which exhibits a data processing device ( 5 ), wherein
 the data processing device ( 5 ) is designed to process a data pair received by a radio tag (T 17 ) in such a way that, knowing the position of the radio tag (T 1 -T 6 , T 10 -T 12 , T 16 , T 18 ) belonging to the respective identifier (Kn) and taking into account the evaluated reception quality (Qn), the position of the radio tag (T 17 ) whose position is unknown can be narrowed down or determined. 
 
     
     
       16. The system ( 4 ) according to one of  claim 13 , wherein the system, preferably an access point (X 1 , X 2 ) of the system ( 4 ), more preferably a data processing device ( 5 ) of the system ( 4 ), is designed to generate information for a located radio tag (T 17 ) that is correlated with the determined location of the radio tag (T 17 ), and the access point (X 1 ), to which the located radio tag (T 17 ) is allocated, is designed to transmit the information to the located radio tag (T 17 ).